Household Electrical Glossary

This page contains an alphabetical listing of household electrical terms and definitions to help in identifying the tools, wiring and devices used for electrical wiring projects around the house.

Electrical Tools and Materials

Amp:

Short for ampere, a unit of measure for current or the volume of electricity running through a circuit. The amp rating for a device or cable determines the amount of current it can safely handle. Typical household circuits begin at 15 amps and go up to 50 or 60 amps.

Electric cable with spiral metal sheathing. Early armored cable, BX cable, carried two electric wires with no ground. The metal sheath served as the ground. Later versions carried an aluminum ground wire, wound in the spiral. Newer armored cable includes an insulated ground wire.

Box:

Electrical or outlet boxes are made of metal or plastic and used to house wire connections including for devices like switches and receptacles, as well as for junction boxes to protect wire splices. Shapes include, square, round, octagonal and rectangular. Sizes up to 4 inches square are available. Use the largest box possible to provide NEC required space for wires and other conductors.

Bus Bar:

A long copper bar inside a service panel or breaker box. All neutral and ground wires are attached to a ground bus bar to complete the electrical path. In some cases a service panel may have separate bus bars for neutral and ground.

Two or more wires housed in a protective sheathing is referred to as electrical cable. Armored, UF and NM are all names for household electrical cable. Each cable type is available for different wire gauge. Standard household electrical cable ranges from 14 awg (american wire gauge) to 6 awg, with 14 having the smallest conductors and 6 having the largest. In household electrical systems 14 gauge wire is used for 15 amp circuits, 12 gauge for 20 amp circuits, 10 awg for 30 amps, 8 awg for 40amps and 6 awg for 50 and 60 amp circuits.

Electrical cable is available with 3 or 4 wires running through the sheathing. Cable with 3 wires is referred to with labels like 14/2 and 12/2, where the two represents the black and white, current carrying wires in the cable. The other wire, the ground wire, is ignored in this labeling. Cable with 4 wires is referred to as 14/3 or 12/3 cable. Here 3 wires carry electricity, the black, red and white. All household cable is available with 2 or 3 current carrying wires and one ground.

Circuit Breaker:

A heavy duty circuit switch located in the service panel and designed to instantly shut off electricity if an overload or short occurs. Circuit breakers are rated for the amount of current they can carry. 15 amp circuit breakers are used with 14 gauge cable for general purpose lighting and receptacle circuits. 20 amp breakers are used with 12 gauge cable for heavier loads such as microwave ovens and dishwashers. 30 amp breakers are used with 10 gauge wire for an electric water heater or clothes dryer. A large kitchen range will require a 50 amp breaker and 6 gauge wire.

Conductor

Anything that will allow electricity to pass through it is a conductor. Metals are typically good conductors with copper being one of the best.

Conduit:

A pipe through which an electrical cable is run to protect it from damage. Conduit is available in metal and pvc plastic. Conduit is required in places like unfinished basements where electrical wiring is exposed and therefore vulnerable to damage.

Continuity:

The uninterrupted path of electricity. A wire from one end to another has continuity, install a switch between the two end and turn it off to break the path and interrupt the continuity.

Current

Electricity that is flowing from one place to another is called current. The volume of electrical current is measured in amperes or amps.

Double-Gang Outlet Box:

A wall outlet box that houses two devices side by side as with two wall switches at a door. Triple-gang boxes are also commonly available to hold three devices in one place.

A rigid, flat metal tape used to run electrical cable through a finished wall or ceiling. The rigid nature of the tape makes it possible to push it past most obstructions in the wall cavity by turning the reel to either side. See Run New Wiring for more about fishing cable.

Fuse:

A safety device used to interrupt the flow of electricity in case of a short or overloaded circuit. These can be made of glass with a threaded base for 120 volt branch circuits, or a cartridge design with a copper cap on each end for 240 volt circuits. Fuses are found mostly in older homes with small, 60 amp service panels.

Flexible metal conduit for running new electric wiring. Another name for armored cable listed above.

Grounding Wire

A safety wire included in a household electrical circuit to carry current directly to ground in case of a short. The grounding wire in household electrical cable is usually bare copper, but it may also be found covered with green plastic insulation.

A safety device designed to instantly break the electrical path if changes in electrical current flow are detected. GFCI receptacles are required in bathrooms, kitchens, garages and unfinished basements, as well as any exterior installation. GFCI circuit breakers are also available for protecting an entire branch circuit.

Hot Wire

A current-carrying wire in an electrical circuit. There may be one or two hot wires in a household electrical circuit. These wires are always insulated and may be colored black or red, or in the case of some ceiling fans, the hot wire may also be colored blue.

Insulator

Anything that resists electrical flow is an insulator. Insulators are needed in electrical circuits to contain the current flow and prevent shorts or electrocution. Vinyl plastic is used as an insulator for household electrical wires.

An electrical outlet box containing a cable splice and covered to protect the connection.

Lineman's Pliers:

Heavy duty wire cutting tool, essential for cutting thick cables.

Multi-Meter:

Test for continuity, voltage, current and resistance. Both analog and digital meters are available. A digital meter is simple to use, easy to read and inexpensive. Analog meters are not as easy use or read and are becoming obsolete.

Needle-nose Pliers:

Handy for tight spaces. Bend wires into a hook when connecting them to screw terminals on fixtures, switches and receptacles.

(Non-metallic cable) Household electric cable with a vinyl plastic sheath used to run electrical wiring through interior walls.

Neutral Wire

A current-carrying wire in an electrical circuit, also called the grounded circuit wire, it serves as the return path for current, and is connected to ground at the service panel. In household electrical circuits the neutral wire is colored white or gray. Some circuits make use of the white or gray wire as a hot wire, when this is done it will be marked with black tape or paint to identify it as hot.

Pigtail

A short piece of wire spliced to circuit wires and capped with a wire nut. Used for making connections to a terminal screw on a device such as a receptacle or to a grounding terminal inside an electrical box.

Receptacle

An outlet for tapping into an electrical circuit usually with an appliance plug. Duplex wall receptacles are the most common type, but larger appliance receptacles are also found in household electrical systems.

A plug-in device that will detect the wiring configuration of an electrical outlet. Through a system of lights this tester will confirm a receptacle is properly wired as well as indicate a problem with the wiring and what the problem is. This is important for polarized, grounded receptacles that can be improperly wired and still power a lamp or other simple test device.

Also called an old-work box, these are electrical boxes with built-in clamps to fasten them into finished walls. All that is needed to install one is to cut a hole the proper size in the hollow part of a wall and insert the box. These can be used in drywall, plaster or paneling. They are best suited for adding wall receptacles and switches. Because they don't offer much support, old work boxes are not a good choice for installing a new ceiling fixture.

Service Panel:

A circuit breaker or fuse box. Electricity enters the household circuitry through the service panel and is distributed from there through circuit breakers or fuses to branch circuits.

Short Circuit:

Unintended flow of electricity from a circuit to a non-circuit conductor. A short can occur when a hot circuit wire touches anything other than its intended contact. A short will cause a circuit breaker, fuse or gfci to instantly shutoff electrical flow to prevent injury or fire.

Switch:

A device for controlled interruption of current flow in a circuit. A single-pole, single-throw (SPST) light switch is the most common type found in household circuits. These have one set of contacts and can be either ON or OFF. A single-pole, double-throw (SPDT) switch has two sets of contacts and can alternate between them to divert current between two separate paths. A 3-way switch is an example of a SPDT household switch.

A two wire cable run from a light fixture to a switch on a wall. Its only function is to control the on and off state of the light.

UF Cable:

Underground Feed cable used to run electricity underground. The sheathing on this cable is thicker and more durable than the NM cable used for interior applications.

Voltage:

The force or pressure that causes electricity to flow, measured in volts. Voltage is also called Electromotive Force (EMF) and is cause by the potential difference in voltage from one end of a circuit to the other. With 120 volts at a circuit breaker and 0 volts at a light fixture, flipping a switch will cause the 120 volts to flow to the 0 volts.

Wattage:

A measure of electrical power. The amount of energy produced and calculated by multiplying circuit current times circuit voltage. (amps X volts = watts)

Wire Nut

Connector for securing and insulating a wire splice where two or more bare wires are twisted together to complete a circuit.

Wire Cutters:

Use these to cut individual wires. Use lineman pliers to cut NM, UF and other thick cables.

Wire Strippers:

Remove insulation from wire without damaging the copper conductor. Most strippers have a cutting notch for wire gauges from #10 to #18. Most wire strippers will also have a cutting edge for quick cuts of individual wires.